SW Louisiana Forecast Discussion...The pesky upper level low and associated weak surface low continues to be the dominant weather feature across the state tonight. As a result temperatures were held below normal today with readings only in the mid 80s at best. Shower and thunderstorm activity was scattered across the area, but was more widespread across Northern portions of the area in closer proximity to the upper level low. The upper level low is currently situated over North Louisiana between Ruston and Monroe. It is cut off from the main Jet Stream which is displaced well to our North right now. That being said, the steering currents over the Bayou State are very weak at this time. Therefore, the upper level low is in no hurry to move out. There are discrepancies in the models as to when this will occur, but we'll try to make heads or tails of this shortly.
It is certain that the upper level low will control the weather across the forecast area once again for Wednesday and Thursday. All is quiet across the area tonight, but a renegade shower or two can't be ruled out after midnight with the upper level low spinning near Monroe. The movement of the upper level low will be erratic and problematic to say the least. The low is forecast to retrograde (move West or WSW) tonight and Wednesday. This will position it back between Shreveport and Tyler during the day Wednesday. This will keep the area under a moist flow around the broad circulation of the low. The end result will be a continued average to above average chance of showers and thunderstorms as disturbances rotating around the upper level low swing through the area along the base of the low. The onshore flow will also induce a sea breeze during the afternoon. Rain chances will vary across the forecast area with the highest chances remaining across Northern portions of the area closer to the ULL, while the smallest chance for shower and thunderstorm activity will reside near the coast. For Thursday, rain chances could increase some further South depending on the movement of the upper level low with some SE motion hinted at by the models. If this occurs, this would place the upper low in Central Louisiana. Rain could occur at any time, but will be more likely during the afternoon. The flooding threat will remain across North Louisiana and into Arkansas where rain has been persistent for the last several days. Cloud cover will continue to be enhanced by this feature with Partly to Mostly Cloudy skies expected for tonight through Thursday. Temperatures will be kept in check as well. Readings very similar to that of Tuesday can be expected for Wednesday and Thursday.
By Friday, the forecast confidence is uncertain at best. The upper level low has to move at some point. It seems that from day to day the models want to delay the departure of this feature. Most model guidance this evening suggests that the upper level low will hang around through Friday, with a nudge a bit to the East from Thursday into Friday. A few models still suggest that the low will weaken and move away from the area overnight Thursday ushering in drier air in its wake, and taking rain chances out of the forecast. Based on what is taking place right now, with the nearly non-existent steering currents, I am going to leave rain chances in the forecast for Friday, but will drop them a bit such as to blend the idea of the models. The temperature forecast for Friday remains unchanged with readings still below normal with another day of enhanced cloud cover. We will remain under the influence of this deep tropical flow off the Gulf until the upper level moves well to our East. By the weekend, the forecast offers improvements as the upper level low finally gets the boot in response to a shift in the Jet Stream. At this same time, a trough and associated cold front will be moving SE through the Rockies. I will talk about this more in a moment. It will be the proverbial kicker for this upper level low, and the low will weaken and lift out to the NE going into the weekend. In the wake of the upper level low, somewhat drier air will move into the area just in time for the weekend. This will reduce rain chances to minimal values, and more sunshine will be expected. As a result, an increase in maximum temperatures is expected as well with readings near to just above normal for Saturday and Sunday. Daytime heating will result in a couple of thermally induced thunderstorms each day, but the overall trend will be for a less than average coverage of rainfall activity. This is good news for all outdoor activities.
In the latter stages of the forecast period, some more changes are in the offing. The cold front mentioned above will be approaching the area at the beginning of the new work week. Ahead of it, moisture levels will increase with an intensifying onshore flow. This will bring rain chances up once again until frontal passage. Shower and thunderstorm activity should remain scattered in nature, with chances returning to near normal to just above for this time of year on Monday. There are still timing discrepancies associated with the movement of the front, and at this point a blended forecast seems to be the logical thinking. The front will be right on cue to usher in the first day of Autumn next week. At this time, the forecast will show frontal passage on Tuesday during the day. Much improved conditions will be ushered in with this front, and temperatures just beyond the forecast period will drop to below normal with lows likely to be in the 50s behind the front by middle of next week. Highs will also drop to the lower 80s with no mention of rain. It should truly be a taste of fall as fall commences next week.
Tropics: The tropics remain quiet as an El Nino pattern exists over the Atlantic basin with a highly sheared environment present. No tropical storm formation is expected through Thursday.
Preliminary Numbers & Zone Forecasts:
LCH 74/84 72/84 73/86 20 40 20 40 20 40
LFT 73/84 72/83 73/85 20 40 20 50 20 40
BPT 75/86 74/85 75/88 20 40 20 40 20 30
AEX 72/81 72/83 71/83 30 50 30 60 20 40
POE 72/81 72/83 71/84 30 50 30 60 20 40
ARA 75/84 74/83 74/85 20 40 20 40 20 40
Tonight...Partly to Mostly Cloudy with a 20% chance of a shower or thunderstorm. Low 74. Light SW wind.
Wednesday...Mostly Cloudy with a 40% chance of showers and thunderstorms. High 84. SW wind 10-15 mph.
Wednesday Night...Mostly Cloudy with a 20% chance of a shower or thunderstorm. Low 72. Light South wind.
Thursday...Mostly Cloudy with a 40% chance of showers and thunderstorms. High 84. SE wind 10-15 mph.
Thursday Night...Partly to Mostly Cloudy with a 20% chance of showers and thunderstorms. Low 73. Light South wind.
Friday...Partly to Mostly Cloudy with a 30% chance of showers and thunderstorms. High 86. SW wind 10-15 mph.
7 Day Outlook for Lake Charles & Vicinity
Wednesday
9-16-09
74/84/40
Wind: SW 10-15
H.I.:90-95
U.V.: 8- High
Thursday
9-17-09
73/84/40
Wind: SE 10-15
H.I.: 88-93
U.V.: 8- High
Friday
9-18-09
73/86/40
Wind: SW 10-15
H.I.: 90-95
U.V.: 9- High
Saturday
9-19-09
70/89/20
Wind: NW 10-15
H.I.: 92-97
U.V.: 10- High
Sunday
9-20-09
71/91/20
Wind: WSW 10-15
H.I.: 92-97
U.V.: 10- High
Monday
9-21-09
73/88/30
Wind: SSE 10-15
H.I.: 90-95
U.V.: 10- High
Tuesday
9-22-09
Autumnal Equinox
74/83/40
Wind: SSE/NNW 15-20
H.I.: N/A
U.V.: 8- High
...Marine Forecast from NWS Lake Charles...
Tonight...West winds 10-15 knots. Seas 1-3 feet. A slight chance of showers and thunderstorms.
Wednesday...West winds 10-15 knots. Seas 1-2 feet building to 2-3 feet in the afternoon. A chance of showers and thunderstorms.
Wednesday Night...West winds 10-15 knots. Seas 1-3 feet subsiding to 1-2 feet after midnight. A chance of showers and thunderstorms.
Thursday...West winds 10-15 knots. Seas 1-3 feet building to 2- 3 feet in the afternoon. A chance of showers and thunderstorms.
Thursday Night...West winds 10-15 knots decreasing to 5-10 knots after midnight. Seas 1-3 feet subsiding to 1-2 feet after midnight. A chance of showers and thunderstorms.
Friday...West winds 10-15 knots. Seas 1-2 feet. A slight chance of showers and thunderstorms.
...Tide Data: Tidal Information Provided is for Calcasieu Pass, LA...
Wednesday Tides:
Low: 8:34a.m. 9:00p.m.
High: 2:59a.m. 12:44p.m.
...Lake Charles Climate Summary from NWS Lake Charles...
Tuesday, September 15, 2009
Low: 73
Normal Low: 70
Record Low: 51-1902
High: 83
Normal High: 88
Record High: 99-1906
Precipitation:
Rain Today: Trace
Month to Date: 3.64"
Normal Month to Date: 3.07"
Year to Date: 45.36"
Normal Year to Date: 41.16"
Record: 3.10"-1930
Sunrise Wednesday: 6:58a.m.
Sunset Wednesday: 7:17p.m.
Good night and God bless!!!
-DM-
No comments:
Post a Comment